Reservoir dogs is similar to Pulp Fiction. A bit simpler, rougher. Good movie, well acted, but a lot of bad guys doing bad things. First time he tried the formula.

I like Jackie Brown. Very slow, great actors - especially the ones you don't have on the list. Calm, interesting, close to no action (just a few seconds here and there). Same structure as Pulp Fiction and Reservoir dogs, but Tarantino left out most of the aggressive coolness and the posing. Also less cynical jokes and more of a consistent story. Even though it lacks the many memorable moments Pulp Fiction had, Jackie Brown is IMHO the better movie.

edit:
The difference between Kill Bill and his earlier movies is that Kill Bill has long, violent action scenes. RD, PF and JB (more harmless) only have short bursts of violence, often as a hook for whole scenes. The whole screen explodes for 10 seconds and then the characters have to deal with the bloody consequences for the next 10 minutes. JB only uses violence as normal part of the story, like every other crime flick.